Various types of video and computer generated information projectors are known. These include, for example, the SharpVision product line commercially available from Sharp Corporation of Japan. Conventional projectors of this type have achieved significant market penetration but suffer from various disadvantages and limitations.
One of the significant limitations in liquid crystal panel projectors lies in the relatively limited amount of light that can be projected. It may be appreciated that the amount of light that can be transmitted through a conventional color liquid crystal panel assembly is limited by the amount of light that can be absorbed by the liquid crystal panel without degradation of its performance and permanent damage thereto inter alia due to overheating. Accordingly the brightness of projected images produced by such projectors is correspondingly limited.
Conventional displays also suffer from limitations in contrast due to their inability to suppress reflection of ambient light.
Various types of projection systems are known in the art for a wide range of applications using various types of light sources, both coherent and non-coherent. Projection systems which employ non-coherent light sources, such as incandescent or arc lamps, have been found by the applicants to display sometimes unacceptable variations in the intensity of light output produced thereby over a projection plane. Such variations may result, inter alia, from non-uniformities, asymmetries and imperfections in the glass envelope of the light source, as well as shadows produced by the light source filament or arc electrodes.
Halogen lamps, such as Model FLT produced by Thorn Lighting Ltd. of Great Britain, are formed with conditioned and segmented reflectors so as to direct light from multiple locations on the light source onto each location in a projection plane. While such a structure does reduce the intensity variation, the reduction is insufficient for certain high quality projection applications wherein the projection plane is relatively close to the light source.